Cross Reference to Related Applications
This application is related to copending applications Ser. No. 853,320, filed Apr. 18, 1986, and Ser. No. 014,418, filed Feb. 12, 1987, which is a continuation of Ser. No. 711,504, filed Mar. 12, 1985, now abandoned.
This invention relates to an absorbable porous tricalcium phosphate, which is suitable as an additive for implant materials based on polyacrylates and/or polymethacrylates, wherein the pores are filled with an absorbable filler which is tolerated by the body.
It is known, for example, from German Offenlegungsschrift No. 2,905,878 (which corresponds to U.S. Pat. No. 4,373,217) that a tricalcium phosphate, which can be resorbed in the body, can be added to implant materials, in particular bone cements based on polyacrylates and/or polymethacrylates, in order to achieve good osseous fusion of the implant with the surrounding bone tissue. The problem that the pores of a porous tricalcium phosphate must be sealed by a suitable filler in order to avoid the pore system taking up liquid acrylate or methacrylate monomers and the disadvantages thereby caused during mixing of the cement has also already been discussed in German Offenlegungsschrift No. 2,905,878. The fillers mentioned therein for sealing the pores are glycerol, water or aqueous salt or buffer solutions, ethylene glycol, low molecular weight polyethylene glycols and lower alcohols, such as ethanol, n-propanol and isopropanol.
In addition to tricalcium phosphate, further additives are proposed or even in fact used for such implant materials, such as, for example, X-ray contrast agents, active compounds, such as, in particular, antibiotics, for controlling infections or fibers for improving the mechanical properties of the implant.
Although each of these additives by itself has a positive influence, there is nevertheless the risk that the mechanical stability and the mixing properties of the bone cement will be adversely influenced by the large number of additives.